Hello. I'm a new player and I have some questions.

Hello fellow redditors. I started playing about a week ago. I finished tutorial and early quests and played about 50 matches by now including 2 arenas. I have some questions for you and would appreciate your help. I have about 700 gold saved and I was wondering what is the best way to spend it. Packs, arena or maybe solo adventures? I also have a couple of gold legendary cards (Nat Pagle and The Beast) and I'm thinking about disenchanting them since I don't really use them. Should I? What kind of cards should I be crafting? I'll probably be playing mage, druid and shaman most of the time since I like them the most. Also any other tips would be very helpful. Thanks for your help. :)